The present invention relates to a feeding mechanism and more particularly to an improved feeding mechanism adopted to sequentially feed single sheets of paper or the like one at a time onto a stacking or accumulation area and to periodically release a stack from the accumulation area when the stack reaches a certain thickness.
This application is an improvement over U.S. Pat. No. 4,799,663 (owned by the same entity which owns this application), U.S. patent application Ser. No. 08/112,193 filed Aug. 26, 1993 (also owned by the same entity which owns this application) U.S. Pat. Nos. 4,640,506 and 5,083,769.
As described and shown in said U.S. Pat. No. 4,799,663, single sheets of paper are moved individually over an inclined ramp and are stacked in a stacking or accumulation area in front of the inclined ramp. The accumulation area is comprised of the front wall of the ramp and a plurality of stop wheels which have notches therein which are spaced forwardly of the ramp and against which the sheets of paper abut. When a predetermined number of sheets are deposited in the accumulation area, the stop wheels are rotated thereby releasing the entire stack for forward movement. When the accumulation area is clear, a new stack of sheets is deposited in the accumulation area and the process is repeated. The structure described in this patent accumulates sheets from the bottom up with the first sheet deposited on the bottom of the accumulating area and subsequent sheets deposited on top of one another until the desired stack thickness is reached.
The mechanism shown and described in said Ser. No. 08/112,193 comprises a sheet feeding mechanism having an accumulator station and a pre-accumulator station in advance of the accumulator station. Sheets of a first group of sheets are fed to the accumulator station. Sheets of a second group of sheets are fed to the pre-accumulator station. The sheets of the second group are stacked in the pre-accumulator station. The first group of sheets from the accumulator station are released and the sheets of the second group are released from the pre-accumulator and fed to the accumulator station after the accumulator station is clear of sheets.
The mechanism described in U.S. Pat. No. 4,640,506 is directed to an attachment to the structure shown in U.S. Pat. No. 4,799,633. With this attachment, the sheets are accumulated in the accumulation area from the top down with the first sheet deposited at the top of the accumulation area and subsequent sheets deposited below the top sheet until the desired stack thickness is reached.
In both of the devices described in said U.S. Pat. Nos. 4,640,506 and 4,799,633 once a stack thickness has been reached, the stack is moved out of the way and a new stack accumulation starts. However, the new stack accumulation cannot begin until after the old stack is removed from the accumulation area. In today's high speed processing sheets, this delay is unsatisfactory since the stacking the sheets cannot meet the number of sheets being fed from some other source, such as a printer.
U.S. Pat. No. 5,083,769 is directed to a dual accumulator in vertical relationship with each other and in which a pivoted ramp is provided which moves from an upper position to a lower position and alternately directs sheets of paper first to the upper accumulator and thereafter to the lower accumulator. It will be appreciated that the use of two accumulators in the manner set forth in this patent creates duplication of effort and increases expenses.
Typically, in the preparation of documents a series of sheets are fed and stacked at a stacking station. The necessary number of sheets have been stacked to form a complete document (such as an insurance policy). The completed stack is moved to some other processing mechanism. With high speed feeding mechanisms, it is possible that when the end of a stack of sheets comprising the first document is being assembled, the first sheets of a second document are also being fed. In this situation, the feeding must stop until the first document is cleared from its stacking station and the sheets of the second document are fed to the stacking station. In addition, with such high speed input feeders it is sometimes possible for a third group of sheets forming a third document to also be fed before the first document is removed from the stacking station. Again, with existing mechanisms the feeding of all these sheets must stop until the stacking area is cleared of documents.